Given that the TV is trying to match one digital frame against another digital frame, you could probably get decent results even with something super naive like downsampling to a very low resolution, quantizing the color palette, then looking for a pixel for pixel match.

All this could be done long before any sort of TV-specific image processing, so the only source of "noise" I can think of would be from the various encodings offered by the streaming service (e.g. different resolutions and bitrates). With the right choice of downsample resolution and color quantization I have to imagine you could get acceptable results.

That's basically what phash does